Seismic
Anisotropy
Modeling from Well Log in Talang Akar Formation, South Sumatra, Indonesia
Thariq Guntoro1, Intan Andriani Putri1, and Dwa Desa Warnana2
Abstract
Old seismic
modeling assume that the
seismic
wave propagate in the earth have a same value for every directions. In the real condition, earth layers is not as ideal as that. It has a very complex structure and a wave do not propagate as ideal as isotropic modeling. It propagate with a velocity which varying with the directions.
Seismic
wave velocity varying with the direction of propagation caused the
anisotropy
characteristics of rock. Because of that, the petrophysical analysis should consider the
anisotropy
parameters. The parameters can be aimed from physical characteristics measurement in laboratory and
seismic
reflection data. In this research, the
anisotropy
parameters or Thomsen parameters generated from well log data. Those parameters are ε, γ, and δ which known as Thomsen parameters. It represent elastics tensor constant aimed from stress and strain relationship in linear anisotropic medium and solid elastic. Generally,
anisotropy
characteristics influence by clay volume fraction, density, and
seismic
wave velocity. In this paper, the effect of clay content to the
anisotropy
analysis in sandstone reservoir discussed. The case study is in G402 well in Talang Akar formation in South Sumatera, Indonesia.
Anisotropy
parameters aimed from the empirical relationship between clay content and body (compressional and shear) wave velocity. The value are ε = 0.14; γ = 0.15; and δ = 0.04. Those value are less than 0.2 so the well has a low
anisotropy
characteristics. Then, anisotropic AVO (Amplitude Versus Offset) equation used to extract synthetics seismogram from isotropy and
anisotropy
model. The different between two models are shown in the synthetics seismogram. The Different of them shows that the
anisotropy
model give the clearer amplitude, thus providing ease of interpretation and reduce the risk of failure in determining the location of the target zone.
AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain